avcodec/jacosubdec: add some memory checks

libavcodec/jacosubdec.c

@@ -168,6 +168,7 @@ static void jacosub_to_ass(AVCodecContext *avctx, AVBPrint *dst, const char *src
 static int jacosub_decode_frame(AVCodecContext *avctx,
                                 void *data, int *got_sub_ptr, AVPacket *avpkt)
 {
+    int ret;
     AVSubtitle *sub = data;
     const char *ptr = avpkt->data;
 
@@ -176,7 +177,6 @@ static int jacosub_decode_frame(AVCodecContext *avctx,
 
     if (*ptr) {
         AVBPrint buffer;
-        char *dec_sub;
 
         // skip timers
         ptr = jss_skip_whitespace(ptr);
@@ -185,9 +185,10 @@ static int jacosub_decode_frame(AVCodecContext *avctx,
 
         av_bprint_init(&buffer, JSS_MAX_LINESIZE, JSS_MAX_LINESIZE);
         jacosub_to_ass(avctx, &buffer, ptr);
-        av_bprint_finalize(&buffer, &dec_sub);
+        ret = ff_ass_add_rect_bprint(sub, &buffer, avpkt->pts, avpkt->duration, 0);
-        ff_ass_add_rect(sub, dec_sub, avpkt->pts, avpkt->duration, 0);
+        av_bprint_finalize(&buffer, NULL);
-        av_free(dec_sub);
+        if (ret < 0)
+            return ret;
     }
 
 end: